In the past, cases for shipping and other applications have been fabricated from plywood panels (with or without plastic skins bonded to the surfaces) joined by attachment to metal edge members (usually by rivets). Such cases could be provided with handles and other attachments by cutting holes in the plywood panels, inserting the desired attachment and riveting the attachment in place.
Such cases were very susceptible to various types of damage when dropped, handled roughly, or generally subjected to localized impacts. The metal edge members were easily bent, the riveted attachments were easily broken or sheared, the holes cut for the attachments could become elongated, and the plywood panels were subject to splintering and delaminating.
Additionally, the cases made from plywood panels were particularly unsuitable for applications requiring an airtight or watertight case. Some air- and water-tightness could be achieved using sealants and gaskets, but the application of such sealants and gaskets was time-consuming and costly. Moreover, with rough handling, an air- or water-tight seal was difficult to maintain.
As cases, generally, and shipping cases particularly, are likely to experience rough handling and localized impacts, it is clear that a case with superior structural qualities is needed. Cases made from molded plastic (injection molding, rotational molding, thermoforming, blow molding, etc.) exhibited some of the desired structural qualities, but did not enjoy the design flexibility of the plywood panel cases.
That is, the plywood panel and metal edge members could be easily cut and sized for a wide range of required case sizes. To produce differently sized molded plastic cases with the desired structural qualities, however, would typically require a new dedicated mold for each separately dimensioned case. Thus a differently sized molded plastic case was expensive and time-consuming to produce. As a result, the design flexibility of the molded plastic cases was limited compared to the plywood panel cases.
With the foregoing problems and concerns in mind, the general object of the present invention is to provide a modular case, most preferably a plastic case, that enjoys superior structural qualities while matching or exceeding the design flexibility of plywood panel cases.